1. Field of the Invention
This invention relates to thermally actuated flow area control for gas turbines particularly thermally actuated vane flow control.
2. The Prior Art
Gas turbine engines frequently require cooling air therein, particularly for high pressure turbine and low pressure turbine rotors. For this purpose, stationary vanes have been installed in such engine locations, i.e., upstream of the above turbine rotors, which cannot take into account variations in engine power and gas flow throughput or engine operating temperatures.
Variable coolant control mechanisms have been attempted in the past which relied on actuation schemes requiring extra moving parts or components, dependence on engine control systems. Such components, though providing benefits of cooling air flow modulation, result in weight addition to such engine. For examples of such prior art, variable stator assemblies, see U.S. Pat. No. 4,135,362 to Glenn, U.S. Pat. No. 4,295,784 to Manning, U.S. Pat. No. 4,664,594 to Mandet et al and U.S. Pat. No. 4,856,962 to McDow.
Accordingly, while there have been either stationary air coolant vanes or pivotable or movable vanes, which are actuated by added components in a gas turbine, there has not been variable coolant flow control in a gas turbine that is uncomplex of construction and light of weight which did not require added control elements for operation thereof and there is a need and market for variable coolant flow vane control that obviates the above prior art shortcomings.
There has now been discovered a lightweight variable coolant flow vane control system that is uncomplex of design, light of weight and responsive to gas turbine operating temperatures.